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The installation of many pile foundations near slopes inevitably exposes them to the influence of the slopes on the stiffness and strength of the soil–pile system, which is a significant issue involving geomechanics and worthy of concern. Therefore, a modified failure wedge model with an optimal base angle is developed to address the impact of slopes on laterally loaded piles in sand, drawing insights from previous experimental results and finite-element analyses. The objective of this model is to provide a more comprehensive and universal analysis of the lateral behavior of piles while considering a limited height slope, compared with previous models applicable in relatively limited cases. In this modified model, factors such as edge distance from the slope crest and slope height are taken into consideration. The proposed theoretical method demonstrates its capability to accurately predict the lateral response of a pile. Based on this method, an analysis is conducted to examine how slope inclination, edge distance from the slope crest, and slope height affect the soil–pile system. [ABSTRACT FROM AUTHOR]

Under various stress paths, the deformation characteristics represented great differences. In this paper, a series of cyclic triaxial tests have been conducted with Fujian standard sand. By comparing the constant deviatoric (CDS) and constant axial stress paths (CAS), the influence mechanism of the cyclic amplitude of the deviatoric stress was discussed. The test results showed that the stress path significantly influenced the volumetric and shear strains. The increasing and decreasing trend in the volumetric strain (ɛv) was consistent with the spherical stress (lnp). Compared with the two stress paths, the slope of the ɛv−lnp curve during the loading and unloading stages was larger under the CAS path. In the CDS path, qc almost did not affect the cumulative volumetric strain, and in the CAS path, the effect was obvious. The shear strain curve was in accordance with the direction of the stress path. As the cyclic number increased, the shear strain gradually accumulated. The shear strain accumulation under the CAS path was larger. The shear strain largely depended on the relative position between the critical state line (CSL) and the stress state of the soil during cyclic loading and unloading. Practical Applications: In practical engineering, the soil will experience various stress paths. For example, in slope or earth–rock dam engineering, where the water level rises and falls repeatedly, the soil often goes through the stress path of constant deviational stress with the cyclic increase and decrease in the spherical stress. In foundation pit engineering, the soil often experiences the stress path of the constant axial stress (CAS) with cyclic loading and unloading of the lateral stress. The stress path greatly influences the deformation and strength of soil. Therefore, the previous two stress paths are compared in this paper to discuss the influence of the cyclic amplitude of deviatoric stress. Under three different consolidation states, the cyclic amplitude of the deviatoric stress significantly influenced the volumetric and shear strains. The shear strain largely depended on the relative position between the critical state line (CSL) and the stress state of the soil during cyclic loading and unloading. Therefore, in practical engineering, if the stress path in the experiment differs from the actual value, the influence of the stress path should be properly considered. The results should be modified according to the degree of influence of each stress condition. [ABSTRACT FROM AUTHOR]

Piled raft foundations (PRFs) below stepped high-rise towers are often subjected to nonuniform triangular-shaped loads with eccentricities. In this study, 20 rectangular piled rafts with different pile configurations and orientations, embedded in medium-dense sandy soil, are analyzed using three-dimensional nonlinear finite-element (FE) analysis in which the critical state–based Clay and Sand Model (CASM) is used as the soil constitutive model. Different triangularly distributed loads with and without eccentricities are considered in addition to uniformly distributed loads. A systematic parametric study is performed by varying the different design parameters based on which the PRF behavior is systematically investigated in terms of multiple performance parameters such as maximum settlement, differential settlement, angular distortion, tilt, and load distribution between the raft and the piles and between the individual piles. It is observed that the pile diameter, number of piles, and raft plan area control the differential settlement, angular distortion, and tilt the most. Based on the insights gained from the parametric study, a design optimization exercise is performed, in which the most optimal pile configuration is selected based on the criteria of allowable settlement and angular distortion with additional considerations for tilt, load distribution, and the volume of concrete required. [ABSTRACT FROM AUTHOR]

In this study, the uplift load-carrying capacity of micropiles was investigated, focusing on the effect of various installation conditions including installation angle (θ), spacing (S), and group configuration. For this purpose, a series of uplift model load tests was conducted using single micropiles (SMP) and group micropiles (GMP). The uplift load capacity of both SMP and GMP increased with θ up to 30° but decreased for a higher installation angle of θ = 45°. Micropile spacing had less effect on the uplift load capacity for GMP. The uplift loadcarrying mechanism of inclined micropiles is proposed based on decomposed axial and lateral loads and resistance components. Based on the proposed load-carrying mechanism, axial and lateral load capacity ratios were proposed and adopted to formulate the uplift load-capacity equation for inclined micropiles. For GMP, the group-effect factor was proposed based on the reduction effect of group micropiles on the overall uplift load capacity. Full-scale uplift load tests were conducted to check the validity of the proposed method. Both SMP and GMP were constructed and tested. It was observed that the estimated results using the proposed method were in good agreement with the measured results. [ABSTRACT FROM AUTHOR]

This paper presents a case history of the successful application of observational method to instruction microtunneling with successive pipe-jacking. The microtunneling project is the construction of four parallel pipes under Guan River in Jiangsu, China. Four parallel tunnels with external diameter of 4,160 mm and horizontally spaced at 4.8 m apart were jacked over 450 m in cemented silty clay and sand by two slurry-balance microtunnel boring machines (MTBM) at a depth of 4.6 m under the river bed. Since the overburden soil is very thin, proper control of tunneling operations was of utmost importance for maintaining the stability of the river bed. In order to optimize the operation parameters prior to construction under the river bed, a field trial was conducted, which included measurement of ground surface settlement, subsurface settlement, and lateral displacement of the subsurface soils, as well as excess pore water pressure and earth pressure. The relationship between ground response and construction operation parameters is summarized. Appropriate operation parameters were applied during tunneling under Guan River. Although tunneling and pipe jacking under the river was successfully carried out, a difficulty was encountered when the MTBM reached the opposite bank and large settlements were observed. This paper discusses the technical issues faced and lessons learnt from interpretation of the monitoring data collected. [ABSTRACT FROM AUTHOR]

Difficulties are often encountered in a variety of seabed sediments during extraction of spudcan foundations of mobile jack-up rigs. This paper reports results from centrifuge model tests undertaken to provide insight into spudcan foundation behavior during vertical extraction through single, double, and multilayer soils. The model tests included half-spudcan tests against a transparent window, allowing the soil flow to be captured continuously by a digital camera and subsequently quantified through particle image velocimetry (PIV) analysis and separate full-spudcan tests to measure the uplift resistance. The observed soil-failure mechanisms provide insight with respect to the profile of extraction resistance. The mechanisms reveal evolving failure modes at different spudcan extraction depths and, in particular, changes in the failure patterns because of varying layer geometry, soil types, and properties. For single, double, and multilayer clays, suction at the spudcan base, shearing along a truncated cone above the spudcan, and weight of the soil above the spudcan constitute the extraction resistance. Maximum extraction resistance occurs in the stiffer soil layer. The extent to which suction is sustained at the spudcan base is critical in determining the extraction resistance. The presence of a sand layer beneath the penetrated spudcan, for example as part of the soil plug pushed down during spudcan penetration, allows the base suction to be released within a short distance of uplift and results in relatively low extraction resistance. Improved understanding of spudcan extraction mechanisms through layered soils resulting from this study will allow development of analytical solutions to model spudcan extraction behavior, assisting jack-up operators to plan properly for leg extraction based on seabed conditions. [ABSTRACT FROM AUTHOR]

The use of new materials for soil strengthening is crucial for geotechnical engineering, especially in foundation construction. Our main objective was to investigate the potential use of two-component water soluble epoxy resins to improve the physical and mechanical properties of medium sand, because the efficacy of these resins on soil strengthening has not yet been properly investigated. Experiments were conducted using resins with different epoxy resin-to-water (ER/W) ratios. The results indicate that the epoxy resins improve the physical and mechanical properties of sand significantly, and if successfully grouted into a formation, the resins could provide a suitable solution for the stabilization of foundation material. Based on the experimental results, a nonlinear regression analysis was performed to correlate the mechanical properties and permeability with curing time and ER/W ratio. [ABSTRACT FROM AUTHOR]

In this study, three-dimensional finite element models, incorporating an elastoplastic material model coupled with isotropic simple softening law, nonassociated flow rule, and shear-band effect, are validated for the evaluation of the shape effect of the square and rectangular vertically uploaded anchor foundations embedded in dense Toyoura sand with embedment ratio of 2 and width of 50 mm. The proposed numerical model has closely predicted experimental uplift load-displacement relationships. The shape effects on the results are also discussed in relation to the progressive failure around the foundations and the shape of the failure boundaries on the ground surface. [ABSTRACT FROM AUTHOR]

Tapered piles in comparison to cylindrical piles can be beneficial in terms of the load capacity. In this paper, estimation of the load capacity for tapered piles using cone penetration test (CPT) resistance was investigated. Fourteen calibration chamber load tests using different pile types and six CPTs were conducted under various soil conditions. From the calibration chamber test results, the total, base, and shaft load capacities were analyzed in terms of soil conditions and taper angle. To evaluate CPT-based load capacity of tapered piles, normalized base and shaft resistances were obtained from normalized unit load-settlement curves. Based on the normalized base and shaft resistances, design equations that can be used to evaluate the base and shaft resistances of tapered piles were proposed. The proposed method is valid for sands of medium to dense conditions, while it may result in unconservative predictions for loose sands. To check the accuracy of the proposed method, field load tests using both cylindrical and tapered piles were conducted and compared with the predictions using the proposed method. A simplified approach using an equivalent cylindrical pile was also investigated and compared. [ABSTRACT FROM AUTHOR]

The capacity of a pile-soil system can be obtained by pushover analysis using the beam-on-nonlinear-Winkler foundation model. When the pile section enters the plastic state, the plastic hinge method is usually adopted to model its postyielding flexural behavior. The propagation of the plastic zone in a pile can be traced using a series of plastic hinges distributed along the pile that is embedded in the soil. This study proposes a proper model for arranging the distributed plastic hinges along the depths of the pile that are prone to yielding. A modified definition of plastic curvature is proposed herein in order to correctly simulate the nonlinear flexural behavior of a pile. Examples are presented to show the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

The existence of large magnitude stresses at the tip of a bearing pile is a well known phenomenon leading to crushing of soil grains and thus affecting pile behavior. Classical foundation design calculations which assume that the soil fails in shear and neglect volume change can be safely used where stress levels or particle strengths prevent crushing, however in the case of weak grains or high foundation stresses consideration should be given to the effects of grain crushing and the resulting volumetric compression. Model pile tests have been carried out in two skeletal carbonate sands and a standard silica sand with the aim of examining the variation of skin friction and end bearing capacities with degree of penetration. The mobilization of the strength of crushable soils requires a much higher strain level while at the same time the end bearing pressure on the model piles exceeded 10 MPa inducing considerable particle breakage. The peak skin friction for all sands occurred at a settlement normalized by pile diameter, S/D, of less than 0.1. At this point the carbonate sands generally had lower skin friction values than the silica sand. Further displacement caused a rapid decrease in skin friction for all three materials. At higher lateral stresses the less crushable Toyoura silica sand generated higher skin frictions. Samples of Chiibishi sand were sectioned and photographed. It was observed that a spherical plastic zone was formed at the base of the pile which expanded with increasing S/D and a degraded layer of broken particles developed around the pile as S/D increased. Large values of the Marsal particle breakage factor were restricted to a zone extending outwards to one pile radius. An end bearing capacity modification factor has been proposed to adapt the conventional bearing capacity equation for soil crushability. This modification factor is a function of soil compressibility and degree of penetration. The factor was shown to decrease with increasing soil compressibility and increase with normalized penetration S/D. [ABSTRACT FROM AUTHOR]

A series of centrifuge model tests is reported that investigated the effects of foundation position on the interaction of reverse, dip-slip faults with shallow foundations resting on sand. The model tests have allowed careful examination of both the soil and foundation deformation as a shear localization (fault) propagates through a 15 m thick sand layer for fault throws up to 5 m. By comparing results of the tests with foundations present with those from a “free-field” test, the effect of the foundation on the faulting pattern has been observed directly. The response of the foundation is very sensitive to the exact position of the fault and even when the fault emerged remotely from the foundation it sometimes caused significant foundation movements. Detailed results are presented for the tests and it is suggested that these results are used as: (1) indications of likely foundation–soil–fault interaction mechanisms; and (2) to allow future validation of numerical models for similar problems. Finally, foundation rotations measured during the fault–foundation interaction tests are compared to those predicted using a simple method based on free-field soil displacements. This simple method makes surprisingly good prediction of maximum fault rotations for different throws. [ABSTRACT FROM AUTHOR]

Numerous cone penetration test (CPT)-based methods exist for calculation of the axial pile capacity in sands, but no clear guidance is presently available to assist designers in the selection of the most appropriate method. To assist in this regard, this paper examines the predictive performance of a range of pile design methods against a newly compiled database of static load tests on driven piles in siliceous sands with adjacent CPT profiles. Seven driven pile design methods are considered, including the conventional American Petroleum Institute (API) approach, simplified CPT alpha methods, and four new CPT-based methods, which are now presented in the commentary of the 22nd edition of the API recommendations. Mean and standard deviation database statistics for the design methods are presented for the entire 77 pile database, as well as for smaller subset databases separated by pile material (steel and concrete), end condition (open versus closed), and direction of loading (tension versus compression). Certain methods are seen to exhibit bias toward length, relative density, cone tip resistance, and pile end condition. Other methods do not exhibit any apparent bias (even though their formulations differ significantly) due to the limited size of the database subsets and the large number of factors known to influence pile capacity in sand. The database statistics for the best performing methods are substantially better than those for the API approach and the simplified alpha methods. Improved predictive reliability will emerge with an extension of the database and the inclusion of additional important controlling factors affecting capacity. [ABSTRACT FROM AUTHOR]

Penetration of skirts is an essential design issue for offshore skirted foundations and anchors in sand. Skirts may not penetrate far enough into dense sand by the available submerged weight alone. It may therefore be necessary to apply underpressure inside the skirt compartment to produce an increased driving force and to reduce the penetration resistance. This paper recommends procedures to calculate penetration resistance and required underpressure for skirts penetrated in dense sand with and without interbedded clay layers. The recommendations are based on interpretation of skirt penetration data from prototypes, field model tests, and laboratory model tests in dense sand. The paper first presents a model to calculate the penetration resistance of skirts penetrated by weight, or other external vertical load that does not cause flow of water in the sand. Two models are considered; one based on bearing capacity equations with friction angles from laboratory tests, and the other one based on empirical correlations with CPT tip resistance. The bearing capacity model gives more consistent correlations with the empirical data than the CPT model. Thereafter, a model to account for the effect of underpressure applied inside the skirt compartment is proposed. This model is developed based on interpretation of available prototype and model test data from skirts penetrated by underpressure. The results show that underpressure facilitates skirt penetration in sand considerably by providing both an additional penetration force and a reduced penetration resistance. It is also shown that interbedded clay layers can prevent flow of water through the sand and eliminate the beneficial reduction in penetration resistance. [ABSTRACT FROM AUTHOR]

Scale effects of shallow foundation bearing capacity on granular materials were investigated to further evaluate the trend of decreasing bearing capacity factor, Nγ, with increasing footing width, B, observed by other researchers. Model-scale square and circular footing tests ranging in width from 0.025 to 0.914 m were performed on two compacted sands at three relative densities. Results of the model-scale footing tests show that the bearing capacity factor, Nγ, is dependent on the absolute width of the footing for both square and circular footings. Although this phenomenon is well known, the current study used a large range of footing sizes tested on well-graded sands to show that the previously reported modifications to the bearing capacity factor, Nγ, using grain-size and reference footing width do not sufficiently account for the scale effect seen in the test results from this study. It also shows that behavior of most model-scale footing tests cannot be directly correlated to the behavior of full-scale tests because of differences in mean stresses experienced beneath footings of varying sizes. The relationship of the initial testing conditions (i.e., void ratio) of the sand beds and mean stress experienced beneath the footing (correlated to footing size) to the critical state line controls footing behavior and, therefore, model-scale tests must be performed at a lower density than a corresponding prototype footing in order to correctly predict behavior. Small footings were shown to have low mean stresses but high Nγ values, which indicates high operative friction angles and may be related to the curvature of the Mohr–Coulomb failure envelope. [ABSTRACT FROM AUTHOR]

Suction caissons are increasingly being used for offshore anchors because of their ease of installation. However, for soil profiles that have sand overlain by layers of silt, there are reasons to believe that it may not be possible to install suction caissons. This may happen because the low permeability of the silt will create a hydraulic blockage, and thus diminish the upward hydraulic gradient required to reduce the penetration resistance in the sand to enable caisson penetration. The tendency of the silt to be sucked up, and its effect on the underlying sand, are not clearly understood. Furthermore, the blockage by the silt layer may be less than if a clay layer is present. This is because scouring of the silt may occur, allowing an upward seepage gradient to develop, and hence causing a reduction in penetration resistance. A series of suction caisson installation tests have been conducted in a geotechnical centrifuge to provide data on the penetration resistance and mechanisms for soil profiles where silt layers are present, either on top, or interbedded between layers of sand. In these tests, the thickness of the silt layer and its depth below the sand surface have also been varied. It has been found that if silt overlies the sand, a larger suction force is required for installation than when installation occurs in homogeneous sand, but that this force is still much smaller than the soil resistance when the caisson is pushed into the ground. When a silt layer is present, the suction pressures are observed to follow a similar trend that is independent of the position and thickness of the silt layer. Scouring of silt was evident in the tests, and significant upward movement of the soil plug inside the caisson was observed in all soil profiles when silt layers were present. The plug height was seen to reduce after the suction was turned off, suggesting that the resulting heave was unstable. [ABSTRACT FROM AUTHOR]

A study of the assumptions involved in the ultimate bearing capacity equation indicates the shortcomings of that equation and load test data confirm these shortcomings. A new approach using a normalized load settlement curve is proposed to alleviate these shortcomings and to obtain the complete load settlement curve for a footing in sand. The normalization consists of plotting the mean footing pressure divided by a measure of the soil strength within the depth of influence of the footing versus the settlement divided by the footing width. It is shown that the normalized load settlement curve for a footing is independent of footing size and embedment. It is proposed to obtain the normalized curve point-by-point from a soil test. Because the deformation of the soil observed under full-scale footings during loading indicates a barreling effect similar to the soil deformation around a pressuremeter probe, the preboring pressuremeter curve is used to obtain the footing curve. The new method consists of transforming the preboring pressuremeter curve point-by-point into the footing load settlement curve. Load tests and numerical simulations are used to propose a method for a rectangular footing near a slope subjected to an eccentric and inclined load. The new method gives the complete load settlement curve for the footing and alleviates the problems identified with the bearing capacity equation. [ABSTRACT FROM AUTHOR]

This note studies settlement ratio, Rs, of pile groups in sandy soils, defined as the ratio of the settlement of a pile group to that of a single pile at the same average load per pile. 31 cases of field pile-group load tests and the corresponding field single-pile load tests were collected for this study. More than one-half of the cases consist of 3-diameter spaced, 9-pile groups. Based on the field test data, statistical analyses of Rs at different load levels were conducted for pile groups with cap-ground contact (PGCs) and pile groups with freestanding caps (PGFs), respectively. The mean of Rs decreases with the load level for both PGCs and PGFs, whereas the coefficient of variation of Rs increases with the load level. The influence of cap-ground contact on Rs does not appear to be significant based on a comparison of the mean Rs values of these PGCs and PGFs. In addition, a comparative study on Rs and group resistance ratio Rr, which is defined as the ratio of the average resistance of a pile in a group to that of a single pile at the same settlement, was conducted to clarify possible misunderstanding between Rs and pile group efficiency factor η for driven pile groups in sandy soils. The value of Rs compares settlement at the working load and is often larger than unity. The value of η compares failure loads, which occur at different settlements for pile groups and their respective single piles. η is usually larger than unity due to soil densification and additional contributions from the cap-ground contact for PGCs. [ABSTRACT FROM AUTHOR]

The ultimate bearing capacity of two interfering strip footings was determined by using the method of stress characteristics. The analysis was performed by choosing two different possible failure mechanisms. The variation of the efficiency factor (ξγ) was computed with respect to change in the clear spacing (s) between the two footings. For a given s/B, the value of ξγ predicted on the basis of Mechanism 1 was always found to be smaller than those on the basis of Mechanism 2. For Mechanism 1, the maximum value of ξγ, which becomes always equal to 2.0, always occurs at s/B=0. On the other hand, the Mechanism 2 provides maximum value of ξγ even greater than 2.0, especially with [lowercase_phi_synonym]>20°, corresponding to s/B=scr/B. It was noted that the results from Mechanism 2 compare more closely with the theory of Stuart in 1962 and with the recent upper bound limit analysis solution of the writers. [ABSTRACT FROM AUTHOR]

Traditional bearing capacity theories for the ultimate capacity of shallow foundations assume that the thickness of the bearing stratum is infinite. The presence of a hard layer within a certain depth below the foundation can significantly influence the unit load supported by the soil. Therefore the original bearing capacity equations should be modified to account for this condition in determining the ultimate bearing capacity. In order to evaluate this phenomenon further, model square and circular footing tests were performed on a bed of well-graded sand. Test beds were prepared at three different relative densities corresponding to loose, medium, and dense conditions: Dr=24, 57, and 87%, using five different sand layer thicknesses, H; H/B values of 0.5, 1, 2, 3, and 4, where B is the footing width. Results of the model scale footing tests show that the bearing capacity factor, Nγ, should be modified up to H/B=3, instead of H/B=1, as previously suggested. The footing shape factor, sγ, should account for both shape and finite layering. This technical note gives a description of the test methods and material used and presents the test results in comparison to previous results. [ABSTRACT FROM AUTHOR]

An attempt is made to establish an analytically based estimate of the influence zone surrounding the tip of a loaded pile in sand. In the framework of the cavity expansion theory and a confined local failure mechanism, explicit expressions are derived in which the sizes of the upward and downward influence zones are properly linked with the angle of shearing resistance, the stiffness, the volumetric strain, and the mean effective stress of the sand at the pile tip. Based on a series of parametric analyses, the mean range of the influence zone is suggested. For piles in clean sand, the influence zone above the pile tip is between 1.5 and 2.5D and the zone below the tip ranges from 3.5 to 5.5D, where D is pile diameter. For piles in more compressible silty sand, the influence zone extends between 0.5 and 1.5D above the pile tip and between 1.5 and 3D below the tip. Because of its analytical nature, the present study may provide a meaningful insight into the current empirical interpretations. [ABSTRACT FROM AUTHOR]

This paper presents results from a full-scale lateral load test on a 0.6 m cast-in-steel-shell (CISS) pile in sand liquefied by controlled blasting. Lateral loads were applied by a hydraulic actuator to simulate seismic inertial forces. The CISS pile was instrumented to provide the data necessary for back calculating lateral soil resistance and displacement. Details of the pile instrumentation and testing procedure are described. The back-calculated soil resistance and displacement are presented as p–y curves and compared to static sand p–y curves. Results from three simplified analyses are presented, where liquefied soil resistance was accounted for by modifying standard static p–y curves, and compared to measured test results. Limitations of the simplified methods are discussed. Test results show the blast induced liquefied sand did not provide resistance to lateral pile movement at displacements up to 50 mm. At displacements of sufficient magnitude, a phase transformation in the sand occurred resulting in a reduction in pore water pressure, and increased lateral soil resistance. The shape of the back-calculated p–y curves for liquefied sand is significantly different from the shape of standard p–y curves. As a result, the modified standard p–y curves do not adequately model the liquefied soil response. Consequently, results from simplified analyses vary from conservative to non-conservative as displacement levels increase. [ABSTRACT FROM AUTHOR]

A lateral load test was performed on a full-scale pile group to evaluate pile–soil–pile interaction effects. The 3×3 pile group at 3.3 pile diameter spacing was driven opened ended into a profile consisting of loose to medium dense sand underlain by clay. The load carried by each pile was measured and strain gages were attached to determine bending moment. A single pile test was conducted for comparison. Group effects significantly reduced lateral resistance for all rows relative to single pile behavior. Trailing rows carried less load than the leading row. In contrast to tests in clay, lateral resistance was also consistently lower for middle piles within each row. Backcalculated p-multipliers were 0.8 for the front row and 0.4 for the trailing row piles which is consistent with results from previous centrifuge tests and full-scale tests where different installation methods were used. Good agreement between measured and computed pile group response was obtained using the p-multiplier approach. Based on centrifuge and full-scale tests in sands, design curves are presented to estimate p-multipliers over a range of pile spacings. The computer program SWM was able to match the measured group response without the use of p-multipliers. [ABSTRACT FROM AUTHOR]

Lateral load test was performed on a full-scale pile group following blast-induced liquefaction to evaluate pile–soil–pile interaction effects. The 3×3 pile group at 3.3 pile diameter spacing was driven into loose to medium dense sand. A single pile test was conducted for comparison. In contrast to preliquefaction tests, group interaction effects were insignificant after liquefaction. The lateral resistance of each pile in the group was similar and about the same as that for the single pile test. p–y curves were developed based on the bending moment versus depth data for Ru values of 95%. While the slope of p–y curves for nonliquefied sand typically decreases with continued deflection, the slope of the backcalculated p–y curves for liquefied sand increases with deflection. This phenomenon appears to be connected with load-induced dilation and a decrease in excess pore pressure locally around the pile. The p–y curves stiffened with depth and as the excess pore pressure ratio decreased. Equations were developed for p–y curves in liquefied sand which also account for the effect of variations in pile diameter. [ABSTRACT FROM AUTHOR]

Discusses a study conducted by Jeffrey A. Fowler and colleagues, which determined the displacement influence factors for elastic shallow soil foundations. Establishment of Young's modulus; Settlement calculations; Difference between the authors' and Schmertmann's methods for calculating settlements of shallow foundations on sand. INSET: Closure by Paul W. Wayne, Member, ASCE, and Harry G. Poulos....

Provides information on a study which presented a design approach to predicting of bearing capacity of shallow foundations on granular soils. Information on the strength and dilatancy of sands related to bearing capacity; Overview of methodology used to develop strength-dilatancy approach; Relative density approach to bearing capacity; Conclusions.

Studies the behavior of sand-fiber-reinforced polymer (FRP) interfaces. Background on foundation engineering; Properties of granular and interface materials tested in study; Interface shear tests.

The behavior of ring foundations on very dense cemented sands was examined by plate loading tests at a flat site located in Kiefan, Kuwait. The effective soil strength parameters c ′ and φ′ were 31 kPa and 36°, respectively. The tests were carried out at a depth of 0.4 m below ground level on 0.6 m diameter solid and ring plates. The latter had inside to outside radii ratio of 0.25, 0.5, and 0.75. The load versus settlement curves for solid and ring plates were compared, with emphasis on the elastic settlement, and on the ultimate bearing capacity. The results indicate smaller settlement at all pressures for ring plates compared with solid plates. However, little or no change in bearing capacity was observed. Tests were also carried out on 0.45 m and 0.3 m diameter solid plates. The purpose being to determine the variation of the settlement ratio with the width ratio for cemented sands. [ABSTRACT FROM AUTHOR]

Provides information on observations on setup and relaxation encountered during installation and testing of piled foundations in a glacial deposit of clean sand. Competition of sand near driven piles; Static and dynamic data for piles in saturated sandy soils.

Addresses the aspect of settlement of reinforced sand foundation with emphasis on bearing capacity. Soil, reinforcement and the interface between the two as important parameters to consider; Utilization of a three-dimensional, nonlinear finite-element analysis; Comparison of the analysis with laboratory results.

Investigates the mechanisms of liquefaction-induced settlement of a shallow foundation, as well as the effectiveness of sand densification by vibrocompaction under the footing. Effect of the depth of soil compacted under the foundation on the footing acceleration and settlement; Modal configuration and instrument layout.

The article presents the author's comments about the article "Estimation of Bearing Capacity of Circular Footings on Sands Based on Cone Penetration Test," by Junhwan Lee and Rodrigo Salgado, published in the April 2005 issue of the journal. The author says that Lee and Salgado must be congratulated for their excellent research on the bearing capacity (BC) of circular footings on sands, based on the use of a nonlinear constitutive model to simulate the behavior of sands.

The article presents the author's comments about the article "Estimation of Bearing Capacity of Circular Footings on Sands Based on Cone Penetration Test," by Junhwan Lee and Rodrigo Salgado, published in the April 2005 issue of the journal. The author says that Lee and Salgado have contributed a lot to the study of shallow foundations. He agrees with their statement that serviceability and ultimate limit states should be treated within the same framework in case of geotechnical engineering.

Focuses on the study `Behavior of Five Large Spread Footings in Sand,' by Jean-Louis Briaud and Robert Gibbens, which appeared in the September 1999 issue of the `Journal of Geotechnical and Geoenvironmental Engineering.' Effects of creep rate on soil behavior; Information on the viscous-elastic-plastic theory; Details on a method based on a dimensional analysis for predicting load-settlement characteristics of prototype footings.